This invention relates to spherical powder particles and to the process for producing the particles which involves mechanically reducing the size of a starting material followed by high temperature processing to produce fine spherical particles. More particularly, the high temperature process is a plasma process.
U.S. Pat. No. 3,909,241 to Cheney et al relates to free flowing powders which are produced by feeding agglomerates through a high temperature plasma reactor to cause at least partial melting of the particles and collecting the particles in a cooling chamber containing a protective gaseous atmosphere where the particles are solidified.
The only commercial process for producing such metal powder particles is by gas or water atomization. Only a small percentage of the powder produced by atomization is less than about 20 micrometers in size. When further size reduction occurs by conventional means the powders tend to agglomerate. Therefore yields are low and powder costs are high as a result.